3G Impala issues

[Nas Escobar]

I got a 2008 Impala for $200 with 140K. It was about to get scrapped for a brake issue but otherwise is a pretty solid car. To fix it, the shop had quoted $2000. The car had other issues and needed to pass inspection so the quote ties in other issues like the headlight being foggy and needing to be replaced, the car not shifting out of park and the key not releasing upon being shifted back to park. Both issues require a push of a tab hidden in the trim. 

 

The plan is to flip it and hopefully make about $300 on it (Would try to sell for $1500 which means I can only spend about $800 on parts.

 

Besides what I mentioned, it has the stupid blender door issues, which seems to be a common GM problem on the W and the Epsilon platform; it has issues with the shifter not shifting out of park and the key not releasing when turned off. I do think the last 2 are related, but not sure if the NSS is to blame. I've been told the p.o. replaced the shift cable numerous times, which would fix the issue but then come back. 

 

Most importantly, my main question is: Did GM keep having issues with the brake booster diaphragms after their fiasco with the braking system on the 1G cars?

 

The car builds pressure when it is off but sinks to the floor upon starting it. It does have an undiagnosed vacuum leak, however I've driven cars with vacuum leaks and they normally do not affect the operation of the brake booster. I don't want to call them related since my understanding is that a car with a disconnected booster vacuum line will typically be extremely hard to push in.  

 

 

All help is appreciated.